Pavement and process of constructing pavements



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' V 3,2&42 B. H. wAn" PAVEMENT PROCESS OF CONSTRUCTING PAVEMENTS Filed Ma v 12. 1926 courses have been laid at substantially the" monolithic structure.

Patented May 1 0, 1927.

BERTRAND H, WAIT, OF NEW ROCHELLE, NEW YORK.

ra'vnmnNr-Ann rnoonss or cons'rnuc'rrne ravnunn rs.

Application filed March 12, 1926. Serial No. 94,212.

My invention relates to articles of manu facture made of concrete, and especially to concrete pavements and other structures suchas sidewalks, platforms, driveways, floors and the'like. It refers particularly to the construction. of concrete slabs which should have a maximum of strength when great savlng 1n the cost-of materials.

considered as a beam, but in which it is desirable that the upper or wearing course should be removable or replaceable without the necessity of removing the entire depth of slab.

Concretepavements have heretofore been constructed in layers which are entirely separated from each other by means of 'intermediate courses of varying character, and in which the upper or wearing course, by reason of this separation or independence, is easily removable. Two course p'avements lIQH E likewise been constructed in which the same time and worked together to form a Concrete pavements of the first class, in which the courses are independent are not as strong as' a monolithic structure of the same depth.v They have the advantage of a removable wearing course, but this course,which acts as a beam more or less independently of the lower course,.must be constructed of comparatively 'Qreat thickness to produce satisfactory results; On the other hand, pavements of the second class, while structurally stronger than pavements of the first class mentioned, do not possess the advantages inherent to a removable top course.

' My invention therefore, in its broad aspects, contemplates a'monolithic pavement or the like and the method of constructing the same whereby the entire slab will act as an integral beam but in which the upper or wearing portion will be readily cleavable from the lower or base portion so that it may be removed when necessary without damage to the lower portion.

The objects of my invention are to provideca pavement and a method of constructing the same as an integral, monolithic slab.

which will have all of the advantages in beam strength of such a slab, but in which a predetermined stratum is provided, along which the upper and lower portions of the pavement are readily separable. Another object of my invention is to provide a method by which a complete two layer pavement of this character may be constructed by a continuous operation, thereby effecting great economy in time and labor. Still an other object of my invention is to provide a concrete pavement in which the maximum quantity of low grade aggregate and the jminimum quantity of high grade aggregate and cement may. be used, thereby effecting a lVith these objects in view my invention includes the hereinafter described process and pavement, an embodiment of which is illustrated in the accompanying drawings in- Fig. 1 is a typical, small scale cross section of my pavement;

Fig. 2 1s an enlarged fragmentary section of the lower course illustrating the preferred method of preparing for the reception of the upper course; l

Fig. 3 IS a section similar to Fig. 2 illustrating a lower course prepared in a slightlydifferent way for the reception of the upper course;

' Fig. 4' is a plan view illustrating in a more or less typical way the fabric which I prefer to incorporate in my pavement; and

Fig. 5 is a highly magnified fragmentary section of the cleavage stratum.

Referring to the drawing, 1 represents the lower course, 2 representsthe uppercourse, and, 3 represents an intermediate course of fabric.

In constructing my pavement the lower course is'first laid upon the subgrade or other foundation and, according to my preferred method, is worked or manipulated by methods well known inv the art so that a thin layer of mortar, 4, is'brought to the,

surface. Upon this mortar surface is laid a fabricated medium, 3, which is pervious to mortar but substantially. impervious to coarse aggregate, and which, for reasons hereinafter mentioned, I prefer to embed slightly in the mortar, or at least to press slightly by a light roller or otherwise, so that the mortar is forced therethrough. The upper course is then placed immediately and before the lower course has attained its initial set, and the surface is finished by the usual methods.

The medium which I propose to use may be of almost any character providedit will divide a stratum of theconcrete into a multiplicity ot spaced, comparatively small or minute areas, '5. For example, ordinary cheese cloth, which is cheap, gives very satisfactory results,-and any fabric or fabricated sired cleavage may be employed. The interstices or perforations in the medium should be of such size that the coarse aggregate cannot project thcrethrough thus providing an interrupted stratum of mortar alone whichis comparatively weak. In connection with the general cha actor of the medium which I propose to employ, 'it is tobe understood that the purpose of this invention is not to strengthen or reinforce the monolith but to render it susceptible to splitting along a predetermined surface or stratum without other- Wise substantiallyaflecting its strength. In other words, the medium which I propose to incorporate is of such character that it weakens rather than reinforces the concrete.

Hence the structural, strength of the medium itself is substantiallyimn'iaterial and for economical reasons 15 preferably light in weight and of slight structural stren th,

Breaking tests have indicated that t 1e concrete is readily cleavable along the plane of fabric and it appears that this results from the separate breaking of the closely spaced minute areas of integrity, 5, between the courses so that the splitting is progressive in character across the zone or stratum of cleavago. On the other hand, breaking tests have demonstrated that a beam constructed with such a cleavage stratum therein has the full strength of. a beam oi the same depth and withoutthe cleavage stratum. The

reasons for this are that the actual area of the strands of fabric is only a small percentage of the total area along the plane of the fabric and there'is a matrix contact between the upper and lower courses for a large percentage of the area of said plane. On the other hand, the matrix is divided into a multiplicity of very small integral parts by the strands of the fabric, and these small parts or sections break one by one when the monolith is split or cleft.

In constructing my pavement the aggregate or mix of either course may be varied as desired. However, it is obvious that cheap.low,grade aggregate and a comparatively lean mixture may be'used in the lower course. By manipulating this course so as to bring the mortar to the surface. and slightly embedding the fabric in this mortar, the cleavage plane will be located in a zone oi: comparatively weak matrix so that separating will be facilitated. On the other hand. slightly embedding the fabric stiiiens up the lower course so that the upper cour=e will not be worked into it. In this way the upper course can he built of a uniform depth and consistency, thus eliminating hair rcaaaea checkin and initial c aching due to uneven depth o i upper course. It 1s to be understood that my process s not 1n any sense limited to the embedding of the fabric in the surface of the lower course or to working the lower course to produce a mortar surface thereon. While I believe the best results are obtained in that way, it is obvious that the fabric may be merely laid upon the lower course either with or without manipulating the lower course to produce a mortar surface. 1

It is also to be understood that my invention is not limited to use in connection with.

concrete comprising coarse aggregate but maybe used with good results in a pavement of mortar alone.

One very great advantage of my pavement over eithera one or two course pavement as heretofore constructed resides in the fact that r the upper course m'aynbe quite thin, and may be laid comparativelydry. and of rich mixturc. The amount of manipulation required by such a course is much less than that requircd by present methods and types of construction and, because of the intermediate .fabric, no poor materials will be worked to the top and cause scaling.

My pavement may, of course, expansion and contraction joints, with steel or other reinforcement, either in the top or bottom or both. and of any mixture or depth, all as required by the trailic, temperature variations, subgrade and other'conditions affecting the design as a structure.

W'hileI have described my invention as particularly applicable to the construction of pavements it is obvious that the invention herein disclosed will be useful in the concrete art generally and it is to be understood that I am not limited in'its a plication to pavements or the like. It is a so to be understood. that the words which I have used in describing my invention and its application are words of description and. not of limitation, and that changes within the purviewof the appended claims may be made without departing from the scope and spirit of this invention.

What I claim is- 1. The process-oi constructing a monolithic pavement or the like havine' a stratum therein along which the monolith may be cleft or split. which comprisesplacimc a course of concrete, working the same to produce a mortar surface thereon, placing on said surface a fabricated medium pervious to mortar but substantially impervious to coarse aggregate. and placing thereover a second course before the setting of the first course.

2. The process of constructing a monolithic pavement or the like having a stratum therein alone which the monolith may be cleft or split, which comprises placing a course of concrete Working the same to probe an an second course before the setting of said mortar.

3. The process of constructing a monov lithic pavement or the like having a stratum therein along which the monolith may be cleft or split, which comprises placing a course of concrete, .placing thereon afabricated medium pervious to mortar but sub-' stantially impervious to coarse aggregate, and placing a second course of concrete thereonbefore the setting of the first course.

4. The process of constructing a monolithic pavement or the like having a predetermined stratum therein along which the monolith may be cleft or split, which comprises permanently embedding in said monolith and substantially coextensive with the cleavage stratum desired, a fabricated medium pervious to mortar but substantially impervious to coarse aggregate.

5. In a concrete pavement or the like, a fabricated medium intermediate the upper and lower surfaces thereof having no appreciable reinforcing effect, but dividing the matrix in the zone of said medium into a multiplicity tively small tum of weakness along which the concrete may be clet't or split. V 6. A concrete pavement or the like, having a stratum of mortar therein divided into a multiplicity of spaced,"comparatively small areas of integrity with the concrete on either side of saidzone, whereby is created a weakened section along which the concrete maybe split or cleft.

7. A substantially monolithic concrete pavementor the like having a mortar pervious fabric of, slight structural strength embedded therein and forming a stratumof comparative weakness along which the concrete may be cleft or split.

8. A monolithic concrete pavement or the like having embeddedtherein a fabricatedmedium pervious to mortar but substantially. impervious to coarse aggregate,- forming a stratum of comparative weakness along which the monolith may be cleft or'split.

-9. A monolithic concrete pavement or the like having a layer of cheese cloth embedded therein and vforming a stratum along which the monolith may be cleft or split.

BERT'RAND: H. WAIT. 

